Multi-position electrical switch with improved contact structure



Au 1, 1967 M. F. BEDOCS ET AL 3,334,198

' MULTI-POSITION ELECTRICAL SWITCH WITH IMPROVED CONTACT STRUCTURE Filed Dec. 29, 1965 2 Sheets-Sheet l INVENTOBS Michael E ocs William Sclzzrzk United States Patent 3,334,198 MULTI-POSITION ELECTRICAL SWITCH WITH IMPROVED CONTACT STRUCTURE Michael F. Bedocs, Wilmette, and William N. Schink, Crystal Lake, 111., assignors to Indak Manufacturing Corp., Northhroolr, Ill., a corporation of Illinois Filed Dec. 29, 1965, Ser. No. 517,259

3 Claims. (Cl. 200-11) This invention relates to electrical switches.

One object of the present invention is to provide a new and improved electrical switch having a relatively large number of operating positions, spaced closely together.

A further object is to provide a new and improved electrical switch which is arranged so that the spacing between the successive operating positions may be substantially less than the spacing between the adjacent contact points of the switch, so that large, rugged contact points may be employed while providing a large number of operating positions.

Another object is to provide a new and improved electrical switch which is extremely compact in construction, yet provides a large number of operating positions.

A further object is to provide a new and improved electrical switch in which a large number of operating positions are achieved by providing a pluarlity of contactors which are engageable with a plurality of groups of contact points, the contact points of the various groups being rela tively staggered so that a circuit is established by each contactor in turn.

It is a futrher object to provide a new and improved switch having one or more insulating bosses or points which are engageable by a contactor as it moves between adjacent contact points, so as to reduce or eliminate the overlapping interval in which the contactor engages both of the adjacentcontact points.

Another object is to provide an electrical switch having a new and improved arrangement for engaging a mounting or retaining'ring.

' Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a somewhat diagramatic front elevational view of an electrical switch to be described as an illustrative embodiment of the persent invention.

FIG. 2 is a side elevation showing the switch and its connector.

FIG. 3 is a rear elevation of the switch, taken along the line 33 in FIG. 2.

FIG. 4 is a disassembled view showing the switch with its contact plate removed, to illustrate the rear sides of the contactors and the front side of the contact plate.

FIG. 5 is an enlarged longitudinal section taken generally along the line 5-5 in FIG. 1.

FIG. 6 is a fragmentary enlarged plan view showing the retaining ring and the lugs or ears for engaging the retaining ring. I

FIG. 7 is a circuit diagram illustrating one possible application of the multi-position switch.

FIG. 8 is a fragmentary sectional view taken generally along the line 8-8 in FIG. 4..

As already indicated, the drawings illustrate an electrical switch 10 which is particularly well suited for antomotive service, but will find many other applications. The illustrated switch is intended particularly for control- 3,334,198 Patented Aug. 1, 1967 ling the speed of a blower motor 12 (FIG. 7) in a heating and air-conditioning system for automobiles or the like. The switch is adapted to be operated by an automatic control unit which may be regulated by a thermostat, so that the speed of the blower motor will be regulated automatically according to the need for heating or cooling of the automobile.

The illustrated switch 10 comprises a casing 14 made of metal or other suitable material. The casing 14 may be of any suitable shape but is illustrated as being square or rectangular in shape. Thus, the casing 14 has a front wall 16 and four side walls 18. The rear of the casing 14 is closed by a contact supporting member or plate 20, preferably made of an insulating material.

As illustrated to best advantage in FIGS. 4 and 5, the switch 10 is provided with a carirage 22 which is movable within the casing 14. The illustrated carriage 22 is of a rotary type. Thus, the carriage 22 has a front shaft or hub portion 24 which is rotatably received in a sleeve member 26 on the front wall 16 of the casing 14. The illustrated sleeve 26 is formed integrally with the front wall 16.

An operating lever 28 may be secured to the front end of the shaft portion 24. In the illustrated construction, the lever 28 has an inner end portion 30 which is seated in a transverse groove 32 formed in the front end of the shaft 24. A rivet or other fastener 34 is provided to secure the lever 28 to the shaft 24. As shown, the outer end of the lever 28 is fitted with a crank pin 36 for connecting the lever to the automatic control unit. It will be understood that the switch may readily be arranged for manual operation, if desired.

The switch 10 is adapted to be secured to a mounting panel 38, which may be provided at some convenient location on the automobile or the like with which the switch is to be used. As shown, the sleeve member 26 extends forwardly through an opening 40 in the panel 38. A locating tab 42 is formed on the front Wall 16 of the casing and is adapted to be received in an opening or slot 44 in the panel 38.

The switch 10 is secured to the panel 38 by a retaining ring 46 which is mounted around the sleeve member 26. The retaining ring 46 is formed with a plurality of arcuate spring fingers 48 for engaging lugs or ears 50 on the sleeve member 26. Each of the fingers 48 is bent to provide a notch or recess 52 which cooperates with one of the ears 50 to provide a detent action. Thus, each of the spring fingers 48 is detained by one of the ears 50'.

The ring 46 is removed by rotating it through approximately 60 degrees in a counterclockwise direction, from the position of the ring as shown in FIG. 1. The ring 46 may then be moved forwardly off the sleeve member 26. Arcuate openings 54 are formed in the retaining ring 46 between the spring fingers 48 to provide clearance for pair of forwardly projecting lugs or handles 56, so that the ring may readily be gasped and manipulated. When the ring 46 is to be installed, it is slipped real'wardlyoverv the sleeve member 26. The openings 54 are aligned with .the ears 50 so that the ring may be slipped past the ears.

The ring 46 is then rotated clockwise through approximately 60degrees so as to move the spring fingers 48 behind the ears 50. The spring fingers 48 are effective to clamp the switch against the rear side'of the panel 38.

In the illustrated construction, the ears 50 are formed in a new and improved manner by lancing or slitting the sleeve member 26 and then bending the cars 50 outwardly. Thus, to form each car 50, the front end of the sleeve 26 is formed with a longitudinal slip 58. The ear is then bent outwardly to form a projection which is triangular in shape. The spring fingers 48 on the retaining ring 46 are engageable with the slit edges 62 of the triangular ears 50. Each of the slit edges 62 provides a stop which is engageable by the outwardly projecting lug 53 on the corresponding spring finger 48 to limit the angular rotation of the retaining ring 46. The slit edges 62 fit snugly into the detent notches 52 in the spring fingers 48 to prevent the accidental loosening of the retaining ring.

The carriage 22 is preferably made of various plastics or other suitable insulating materials. As. shown to best advantage in FIG. 5, the carriage 22 is formed with a rear shaft member 64 having a reduced rear portion 66 which is rotatably received in a central opening 68 formed in the contact supporting plate 20. A longitudinal bore 70 is formed in the carriage 22 to receive the rivet 34 which is employed to secure the operating lever 28 to the front end of the carriage. The bore 70 opens from the rear of the carriage 22 and extends through the rear shaft portion 64 and the main or body portion of the carriage 22, and also part way through the front shaft portion 24.

The insulating carriage 22 is preferably provided with a plurality of contactors 72 which are movable with the carriage. Two such contactors 72 are provided in the illustrated switch. Each contactor 72 is pressed or biased rearwardly by a spring 74 which is preferably in the form of a compression coil spring. The illustrated springs 74 are received in bores or recesses 76 formed in the rear side of the carriage 22. The rear end of each spring 74 is located and retained by a projection or boss 78 which is formed on the corresponding contactor 72.

Each contactor 72 is located and retained on the carriage 22 by a pair of prongs or tabs 80 which project forwardly from the contactor. Slots or recesses 82 are formed in the carriage 22 to receive the prongs 80. It will be understood that the prongs 80 are slidable forwardly and rearwardly in the slots 82.

The contactors 72 are movable into engagement with a series of contact points and insulating bosses, mounted on the front side of the contact supporting plate 20. The arrangement of the contact points and insulating bosses will be described in detail presently. Each of the locating prongs 80 on the contactors 72 is preferably formed with a tapered front end portion 81, to enable the contactors to rock appreciably as they move up and over the various contact points. In addition, each of the slots 82 is preferably formed with a tapered front end portion 83 to provide for such rocking movement of the contactors. Each of the contactors 72 is preferably arranged to establish circuits between a contact ring 84 and the various contact points. In the illustrated construction, each of the contactors 72 engages the contact ring 84 at all times, in all of the operating positions of the switch. The contact ring 84 is in the form of an annular plate of copper or other suitable material, mounted on the front side of the insulating plate 20. As illustrated, the contact ring 84 has an outwardly extending radial arm 86 which is secured to the insulating plate 20 by a contact ring 88 which extends through the arm 86 and the insulating plate 20. A terminal or prong 90 is secured against the rear or external side of the insulating plate 20 by the rivet 88. The contact ring 84 is located on the plate 20 and is prevented from rotating about the rivet 88 by a tab 92 which projects rearwardly from the ring, into an opening 94 formed in the plate 20.

Each contactor 72 is preferably provided with one or more rearwardly projecting contact bosses or points 96 to ride along the contact ring 84 when the carriage 22 is rotated. It is preferred to provide a pair of such contact bosses 96 on each contactor, so that each contactor will have three points of contact with the contact ring and the various contact points. To engage the contact points, each contactor 72 is preferably provided with an outwardly projecting radial arm 98, formed with a rearwardly projecting ridge or boss 100. However, the contactor may assume a variety of shapes and forms. Each of the illustrated ridges 100 is generally cylindrical in curvature and is rearwardly convex.

To provide a multiplicity of positions, the switch 10 is preferably provided with a considerable number of contact points 102, mounted on the rear side of the insulating plate 20. Twelve of the contact points 102 are provided in the illustrated switch. For individual identification, the contact points 102 are designated 102A-L in FIGS. 4 and 7.

The contacts 102A-L are arranged in two groups, corresponding to the two contactors 72. The contacts 102A- F form one group and are adapted to be engaged by one of the contactors 72. The second group comprises the contactors 102G-L, which are adapted to be engaged by the other contactor 72.

Generally speaking, the contacts of one group are staggered or offset relative to the contacts of the other group, so that the two contactors establish successive circuits in turn. This arrangement makes it possible to provideapproximately twice as many operating positions as would be possible with a single contactor.

In the initial or OFF position of the switch, one of the contactors 72 engages the contact rivet 88 which is connected to the contact ring 84, so that no circuit is estab lished by this contactor. In FIG. 7, the contactors 72 are shown diagrammatically in full lines in their initial posi tion-s. It will be seen that the other contactor 72 is between the contact points 102A and 102D so that no circuit is established by this contactor. An insulating boss or projection 104 is provided on the insulating plate 20 between the contacts 102A and 102D for engagement by the contactor. This particular insulating boss 104 is generally triangular in shape, to occupy most of the space between the contact points 102A and 102D, but the boss 104 has a rounded inner portion opposite the contact ring.

84. The boss 104 is preferably in the form of a semiperforation, pressed or offset from the insulating plate 20.

When the contactors 72 are rotated clockwise from their initial positions of FIG. 7, the lower contactor 72 moves from the insulating boss 104 into engagement with the contact point 102A so as to establish a circuit between'this contact point and the contact ring 84. The upper contactor 72 moves into a position between the contact rivet 88 and the contact point 102]. A rearwardly projecting insulating. boss 106 is preferably provided on the insulating plate 20 between the contact points 88 and 102] for engagement by the contactor. The insulating boss 106 is preferably in the form of a semi-perforation pressed or offset from the insulating, plate 20. The boss 106 holds the contactor 72 away from the contact points 88 and 102] and prevents the contactor from engaging both contact points simultaneously. Moreover the insulating boss 106 promotes the smooth and easy movement of the contactor between the rearwardly projecting contact points 88 and 102]. As already indicated, the contact points 102A and 102] are staggered or offset relative to each other so that the diametrically opposite contactors 72 engage the contact points in sequence rather than simultaneously. The insulating boss 106 is diametrically opposite from the contact point 102A.

When the contactors 72 are moved an additional amount in a clockwise direction, they come into their third operating position, in which the upper contactor engages the contact point 102]. The lower contactor 72 is between the contact points 102A and 102B. An insulating boss 108 is preferably provided on the insulating plate 20 for engagement by the lower contactor in this position. The insulating boss 108 projects rearwardly from the plate 20 and preferably is in the form of a semi-perforation pressed or offset from the plate. The boss 108 projects rearwardly to a suflicient extent to hold the lower contactor away from the rounded contact points 102A and 102B so as to prevent the contactor from forming a bridge between the contact points in this position. Thus, thespacing between the contact points 102A and 102B may be made quite close while preventing or minimizing the bridging action of the contactor between the contact points.

A further clockwise movement of the contactors 72 brings them to their fourth operating position, in which the lower contactor engages the contact point 102B to establish a circuit between this contact point and the contact ring 84. The upper contactor is between the contact points 102] and 102K. Another insulating boss 110 is preferably provided in this location, to hold the contactor away from the contact points 102] and 102K. The boss 110 is preferably in the form of a semi-perforation pressed rearwardly from the insulating plate 20.

Further clockwise movement of the contactors 72 brings the upper contactor against the contact point 102K, in the fifth operating position of the switch. The lower contactor is between the contacts 102B and 102C. In this particular switch, the contact points 102B and 102C are connected together, so that there is no need to provide a semi-perforated boss between these contact points. Similarly, the contact points 102K and 102L are connected together. The contact point 102C represents an extension of the contact point 102B. Likewise, the contact point 102L represents an extension of the contact point 102K.

The contactors 72 may be moved counterclockwise from the initial position of FIG. 7 to four more operating positions which will be designated the sixth through the ninth positions. These additional positions correspond generally to the second through the fifth positions. In the sixth position, the lower contactor 72 engages the contact point 102D, while the upper contactor engages an insulating boss 112, preferably in the form of a semiperforation pressed rearwardly from the plate 20 between the contact points 88 and 102G. In the seventh position, the upper contactor 72 engages the contact point 102G, while the lower contactor engages another insulating boss 114, between the contact points 102D and 102E.

In the eighth position, the lower contactor engages the contact point 102E, while the upper contactor engages still another insulating boss 116, preferably in the form of a semi-perforation pressed rearwardly from the plate 20 between the contact points 102G and 102H. In the ninth position, the upper contactor 72 engages the contact point 102H, while the lower contactor is between the contact points 102E and F. In this particular switch, the,

contact points 102E and F are connected together, so that the contact point 102F represents an extension of the contact point 102E. Similarly, the contact points 102H and 1021 are connected together.

The semi-perforated bosses 106, 108, 110, 112, 114 and 116 are preferably circular in shape and are of a height corresponding generally to the height of the contact points 102. The insulating bosses are spaced somewhat farther from the contact ring 84 than are the contact points 102, but the contact ridges or bars 100 on the contactor 72 extend outwardly a sufiicient distance to engage the insulating bosses, as well as the contact points. Preferably, the bosses are flat-topped.

v The illustrated switch can be employed to establish nine different sets of circuits for the nine different positions. However, in thisparticular switch the corresponding contact points on the opposite sides of the initial position of the switch are connected together so that the circuits established by the switch are the same in the sixth through the ninth positions as they are in the second through the fifth positions. It will be evident from FIG. 3 that the contact points 102A and D are connected together by a bar or plate 118 which is formed with a terminal or prong 120. The contact points are in the form of rivets which extend through the plate 20 and are employed to secure the terminal bar 118 to the rear side of the plate.

In this particular switch, the contact points 102B, C, E and F are all connected together by means of a bar or plate 122 which is formed with a terminal prong 124. The contact points 1026 and J are connected together by a bar or plate 126 which is formed with a terminal prong 128. The remaining contacts 102H, I, K and L are all connected together by a plate 130 which is formed with a terminal prong 132.

As indicated in FIG. 2, the terminal'prongs 90, 120, 124, 128 and 132 are arranged to receive a connector or receptacle 134, whereby the desired circuit connections may be made to the switch. The receptacle 134 may readily be connected to and disconnected from the switch.

The side walls 18 of the casing 14 are preferably formed with a plurality of tabs 136 for securing the insulating plate 20 to the rear side of the casing. The illustrated tabs 136 extend through locating notches 138, formed in the edges of the plate 20, and are bent inwardly behind the plate 20.

As already indicated, FIG. 12 illustrates one possible circuit whereby the switch 10 may be employed to control the speed of the motor 12 which may be employed to operate a blower in an automotive heating and ventilating unit. The speed of the motor 12 may be varied by introducing a series of resistors 141, 142, 143 and 144 into the circuit between the motor 12 and the automotive battery 146. This circuit also includes a switch 148, which may be the ignition switch of the automobile. The switch 148 is connected between the battery 146 and a lead 150 to which the contact point 88 is connected. Thus, when the switch 148 is closed, the battery voltage is supplied to the contact point 88 and the contact ring 84, and thence to the contactors 72.

When the switch 10 is in its initial or OFF position, all of the resistors 141144 are connected in series with the motor 12, so that it operates at low speed. A lead 152 is preferably connected between the junction of the resistors 141 and 142 and the contact points 102A and D. Another lead 154 is connected between the junction of the resistors 142 and 143 and the contact points 102G and J. The junction of the resistors 143 and 144 is connected by means of a lead 156 to the contact points 102B, C, E and F. The other end of the resistor 144 is connected to the contact points 102H, I, K and L by means of a lead 158. As the contactors 72 are moved to successive positions on either side of the initial position, the resistors 141144 are successively short-circuited so that all of the resistors are out of the circuit in the fifth and ninth positions of the switch. In these positions, the motor 12 operates at full speed.

It may be helpful to offer a brief summary of the operation of the illustrated switch 10. In FIG. 7, the con tactors 72, shown diagrammatically, are illustrated in full lines in the initial or OFF position of the switch. The upper contactor 72 engages the battery contact point 88, while the lower contactor engages the insulating boss 104.

When the contactors 72 are rotated clockwise to the second operating position, the lower contactor engages the contact point 102A, While the upper contactor engages the insulating boss 106. Thus, the lower contactor establishes a circuit between the contact ring 84 and the contact point 102A so as to short-circuit the resistor 141. Accordingly, the motor 12 operates at a speed somewhat greater than its lowest speed.

In the third operating position of the switch, the upper contactor engages the contact point 102], so as to shortcircuit the resistors 141 and 142. The lower contactor engages the insulating boss 108.

In the fourth operating position, the lower contactor 72 engages the contact point 102B, so as to short-circuit the resistors 141, 142 and 143. The upper contactor engages the semi perforated boss 110.

When the switch is moved to its fifth position, the upper contactor engages the contact point 102K so as to shortcircuit all four resistors 141-144. The lower contactor is between the contact points 102B and 102C, but has no effect on the circuit because all of the resistors are already short-circuited. The motor 12 is supplied with full battery voltage so that it operates at high speed.

The contact point 10'2L extends the fifth position of the switch, because this contact point is connected to the contact point 102K. As the upper contactor moves between the contact points 102K and L, it continues to short-circuit all four resistors 141-144.

For the sixth through the ninth positions, the contactors 72 are moved counterclockwise, in the opposite direction from the initial position. In the sixth position, the lower contactor engages the contact point 102D, while the upper contactor engages the semi-perforated insulating boss 112. The circuit is the same as for the second position.

In the seventh position, the upper contactor 72 engages the contact point 1026, while the lower contactor engages the insulating boss 114. The circuit is the same as for the third position.

In the eighth position, the lower contactor engages the contact point 102E, while the upper contactor engages the boss 116. The circuit is the same as for the fourth position. Finally, in the ninth position, the upper contactor engages the contact point 102H, while the lower contactor is between the contact points 102E and F. The contact point 1021 extends the ninth position to a greater angular interval.

The provision of two contactors and two sets of relatively staggered contacts makes it possible to double the number of active positions of the switch, for the same range of angular movement. The provision of the insulating bosses 106-116 eliminates excessive overlapping between the successive positions, so that the contact points may be arranged with only a minimum spacing therebetween. As each contactor passes between the adjacent contact points, it engages the intermediate insulating boss and is held away from the adjacent contact points so that the bridging action of the contactor is avoided or minimized.

Inasmuch as the switch is capable of providing a large number of closely-spaced operating positions, the switch is extremely well adapted for operation by an automatic control device, such as a servo uni-t or the like. Typical angular dimensions are indicated in 'FIG. 1, showing the close spacing between the various positions. It will be seen that the OFF position extends for 16 degrees on either side of the central position, at which the upper contactor of FIG. 7 is centered over the contact point 88. The second and sixth positions, by which the blower motor is operated at medium low speed, extend for 12 degrees from 16 to 28 on either side of the central position.

The third and seventh positions, at which the blower motor is operated at medium speed, extend for '12 degrees from 27 to 39 on either side of the central position. It will be noted that there is a slight overlapping between the successive positions, so that a new circuit is made by the switch before the previous circuit is broken.

The fourth and eighth positions extend for 16 degrees from 38 to 54 on either side of the central position. These positions represent medium high speed operation of the blower motor. Here again there is slight overlapping "between the successive positions.

The fifth and ninth positions, representing high speed operation of the motor, extend for 16 degrees from 49 to 65 on either side of the central position. A further extension of the high positions is normally brought about by the extra contact points 1021 and L.

It will be evident that the illustrated switch provides a multiplicity of operating positions in a relatively small range of movement of the carriage. Moreover, the switch provides the multiplicity of positions in an extremely compact construction. By virtue of the ingenious construction of the switch, the multiplicity of positions are achieved without resorting to a complex or expensive arrangement Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

We claim:

1. In an electrical switch,

the combination comprising a housing,

a carriage made of insulating material and rotatable in said housing,

a pair of diametrically opposite contactors mounted on the rear side of said carriage,

said contactors being separate and insulated from each other on said carriage,

a contact supporting plate mounted on said housing to the rear of said contactors,

a contact ring mounted on said plate and engaging said contactors throughout the range of movement thereof,

a pair of groups of contact points mounted on said plate and engageable by said contactors,

one of said contactors being engageable with each of said groups,

each of said contactors having rearwardly projecting inner contact means engaging said contact ring and rearwardly projecting outer contact means for engaging said contact points,

said points of one of said groups being staggered relative to said points of the other group whereby said contactors engage said points in turn to increase the number of operating positions of said switch,

and a plurality of insulating bosses disposed on said plate and interspersed between certain of said contact points for engaging said contactors as said contactors pass between the adjacent points.

2. In an electrical switch,

the combination comprising a housing,

a carriage made of insulating material and rotatable in said housing,

a pair of separate diametrically opposite contactors mounted on the rear side of said carriage,

a contact supporting plate mounted on said housing to the rear of said contactors,

a contact ring mounted on said plate and engaging said contactors throughout the range of movement thereof,

a pair of groups of contact points mounted on said plate and engageable by said contactors,

one of said contactors being engageable with each of said groups,

each of said contactors having inner contact means engaging said contact ring and outer contact means for engaging said contact points,

said points of one of said groups being staggered relative to said points of the other group whereby said contactors engage said points in turn to increase the number of operating positions of said switch,

and a plurality of insulating bosses disposed on said plate and interspersed between certainof said contact points for engaging said contactors as said contactors pass between the adjacent points,

each of said contactors being provided with a pair of rearwardly extending projections for engaging said contact ring and a third rearwardly extending projection for engaging said contact points.

3. In an electrical switch,

the combination comprising a housing,

a carriage made of insulating material and movable in said housing,

a contactor mounted on the rear side of said carriage,

a contact supporting plate mounted on said housing to the rear of said contactor,

9 10 a plurality of contacts mounted on said supporting contacts, said tapered openings being of increasing member and engageable by said contactor, Width from the rear toward the front of said carriage.

spring means disposed between said carriage and said contactor for biasing said contactor rearwardly, References Clted said contacto'r having a plurality of locating prongs pro- 5 UNITED STATES PATENTS jecting forwardly herefrom, 2,937,245 5/1960 Long 200-16 said carriage having openings in the rear side thereof 3,183,316 5/ 1965 Roeser 20011.24 for receiving said prongs, 3,223,794 12/1965 Hoy et a1 ZOO-16 each of said openings in said carriage being tapered in I width to enable said contactor to rock relative to 10 ROBERT SCHAEFER, Examinersaid carriage as said contactor is moved over said J. R. SCOTT, Assistant Examiner. 

1. IN AN ELECTRICAL SWITCH, THE COMBINATION COMPRISING A HOUSING, A CARRIAGE MADE OF INSULATING MATERIAL AND ROTATABLE IN SAID HOUSING, A PAIR OF DIAMETRICALLY OPPOSITE CONTACTORS MOUNTED ON THE REAR SIDE OF SAID CARRIAGE, SAID CONTACTORS BEING SEPARATE AND INSULATED FROM EACH OTHER ON SAID CARRIAGE, A CONTACT SUPPORTING PLATE MOUNTED ON SAID HOUSING TO THE REAR OF SAID CONTACTORS, A CONTACT RING MOUNTED ON SAID PLATE AND ENGAGING SAID CONTACTORS THROUGHOUT THE RANGE OF MOVEMENT THEREOF, A PAIR OF GROUPS OF CONTACT POINTS MOUNTED ON SAID PLATE AND ENGAGEABLE BY SAID CONTACTORS, ONE OF SAID CONTACTORS BEING ENGAGEABLE WITH EACH OF SAID GROUPS, EACH OF SAID CONTACTORS HAVING REARWARDLY PROJECTING INER CONTACT MEANS ENGAGING SAID CONTACT RING AND REARWARDLY PROJECTING OUTER CONTACT MEANS FOR ENGAGING SAID CONTACT POINTS, SAID POINTS OF ONE OF SAID GROUPS BEING STAGGERED RELATIVE TO SAID POINTS OF THE OTHER GROUP WHEREBY SAID CONTACTORS ENGAGE SAID POINTS IN TURN TO INCREASE THE NUMBER OF OPERATING POSITIONS OF SAID SWITCH, AND A PLURALITY OF INSULATING BOSSES DISPOSED ON SAID PLATE AND INTERPERSED BETWEEN CERTAIN OF SAID CONTACT POINTS FOR ENGAGING SAID CONTACTORS AS SAID CONTACTORS PASS BETWEEN THE ADJACENT POINTS. 